Study finds smoking marijuana and cocaine can cause cancer

WASHINGTON (CNN)-- In the first study of its kind, researchers found that
smokers of marijuana and crack cocaine show the same kinds of precancerous
conditions caused by smoking tobacco.

The findings were released Tuesday in the Journal of the National Cancer
Institute.

In the study, researchers examined samples of respiratory tract tissue from
participants who ranged in age from 21 to 50. To be eligible, the participants
had to be in one or more of the following categories: Marijuana smokers who
smoked an average of 10 or more marijuana cigarettes a week for the last five
years or longer; crack cocaine smokers who smoked one gram or more of crack
cocaine a week for nine months or longer within the past year; or tobacco
smokers who smoked 20 cigarettes or more a day for the last five years.

The researchers looked at genetic markers known to be associated with
increased risk of lung cancer. Changes or overproduction of some markers were
found in a majority of the study participants.

The findings suggested that tobacco was not the only smoked substance that
set the changes preceding lung cancer development in motion.

The study also showed that habitual smoking of tobacco, marijuana or crack cocaine in combination could potentially lead to more
cancerous alterations in the molecular makeup of cellular structure than
single-smoking alone.

Dr. Sanford Barsky, co-author of the study and a member of the University of California, Los Angeles' Jonnson Comprehensive Cancer Center, said he was not surprised by the findings. He said any substance that is inhaled, regardless of chemical makeup, releases carcinogens into the lungs and throat.

In an editorial accompanying the study, Dr Li Mao and Dr. Yun Oh at the
University of Texas's M.D. Anderson Cancer Center conclude that the nationwide teen anti-tobacco effort might have an "unintended consequence" -- teens will
substitute tobacco with marijuana.

They write while these anti-tobacco campaigns are expected to reduce
the numbers of teenagers and children who smoke tobacco cigarettes, the rate of marijuana use is increasing.

They note the percentage of students smoking marijuana on a daily basis has risen from 1.9 percent in 1992 to 4.6 percent in 1995.